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New house, new Trane Equipment-not cooling properly

Hi everyone. I am having problems cooling my house in the daytime. This site has many knowledgeable people and posts, so I hope you can give me some ideas. Sorry in advance for the long post—I am trying to give you all the info you could need.

Background: I just purchased my first house, a new construction home, 2396 sq ft, with new Trane equipment:

Problem:
The system will not cool the house in the afternoon and evening hours. The temp keeps rising on the thermostat and the system runs constantly from around noon or 1pm and shuts off around 11pm. I keep it on 73-74 and the temp goes up from there… Usually tops out at 78, 79, or 80. We sealed the equipment in the attic closet—it was nice and cool in there before the patches were put on!

Actions Taken:
HVAC Tech #1 (Hired by builder): Added refrigerant on his first service call.
Moved the attic fan to another part of the attic on his most recent service call.

Readings, and written evaluation by HVAC Tech #2:
Outdoor unit was overcharged. Showing 33-degree subcool. Pressures were 315 and 95. Delta-T was 8-degrees. Pulled overage out. Got down to 15-degree subcool with a 19-degree Delta-T. tried for 10-degree subcool, which is manufacturer’s recommendation, but the Delta-T decreased. Suction pressure dropped more than the head pressure. It dropped to 65 pounds. Added more refrigerant to reclaim Delta-T until unit is properly fixed. Pressures are now 190 and 85 with the current charge. There is a 10-degree loss between supply at plenum and closest supply vent. Recommend vacuuming the system and recharging.

Everything is insulated in the attic. 2 people said there weren’t any problems up there. I found one return that wasn’t pulling any air in—that was not connected and was pulling attic air into the system. That has been fixed but the problem still exists. Another note: Neighbors (and the model homes) with the same sq ft and equipment are not having this problem. My line outside won’t sweat and is only cool. The others are all cold and sweaty. Any ideas? I don’t know what to do at this point. Thanks in advance for anything you could suggest.

Well first off, why did the contractor have to "HIRE" someone to come out and look at the problem? Didn't he have an installing company who warrants what they do? The GC is responsible for all problems that surface within the first 12 months of your ownership. If a problem begins within the 12-month period and is not remedied before the 12-months is expired, the GC still owns the problem until it is properlyl resolved. So you should be paying zero for any repairs.

Sound like #2 knew more than #1 or at least cared enough to do a better analysis. But there could be many issues. We don't have enough info to really give a good answer. You could have excessive duct leakage, insufficient insulation, insufficient airflow, restricted ducts (high static) or a refrigeration problem that could be non-condensibles or a TXV problem. So my advice is to first make it very uncomfortable for the GC. He/she has an obligation and needs to live up to it. Second, whoever comes into your home needs to get the following readings at a minimum: IWB, DB @ return plenum, DB @ supply plenum, DB at return grille, DB at the furthest supply diffuser, OAT, SH, SC. Don't worry about what those letters mean. If it's a pro, he/she knows what they mean and doesn't need the list anyway because those are the minimum readings the tech would take anyway. From those readings, a good tech can determine refrigerant charge, airflow across the coil, whether you've got substanial duct leakage or other duct problems and can form a good opinion on whether the equipment is operating at 100% capacity and just isn't big enough or whether there's a duct or mechanical problem. Mind you now, finding techs with that kind of knowledge can cost significant dollars so if the GC is price shopping, you're going to be uncomfortable for very long time. See my signature below.

If YOU want change, YOU have to first change.

If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

Nice quote. Thanks for the info. He does have a contract for one year. I am only 2 month in. I will call the builder again and have their tech (Tech #1) sent out, but this time, I will ask him to find all those values. It is going to be painful again. He has kept me at home from work waiting for 5 days so far--didn't show up (or even call). Last time he was here, he wouldn't hook up his gauges to the outdoor unit. He told me that he remembers the numbers from two weeks ago and said that the attic fan was the problem. The attic fan didn't change anything. I am now resorting to feeling other people's air conditioning vents when in their houses to compare to mine. Much colder than what my system puts out!

Thanks again! Hope I don't have to wait another 2 weeks for him to finally show up and find these values!